A plumber from Cardiff who was diagnosed with cancer said he had to continue working while undergoing treatment to make ends meet, despite doctors advising him not to.
Father-of-five Lewis Griffiths said he had to go against medical advice and work through "sickness and exhaustion" in order to pay bills.
Without family support, the 34-year-old said he would "probably have lost everything".
It comes as a major inquiry into cancer inequalities in Wales has revealed an extra 2,000 diagnoses a year are linked to deprivation - equating to more than five avoidable cases a day.
Cancer Research UK and a cross-party group of Senedd members found lung cancer accounts for around half of those, with obesity-related cancers also being prevalent in poverty-stricken communities.
Mr Griffiths was diagnosed with Hodgkin Lymphoma - a type of blood cancer - last year and said his treatment caused side effects such as sickness and exhaustion.
"Nurses just said concentrate on yourself, try and stay out of the dust and things like that, so it came to the point where I just had to quit work completely," he said.
"It was hard, very hard. My mrs was trying to work when she could and bring in money, we had family and friends that were there to support us but I know people out there that haven't got that and it's a tough thing to have to go through.
"If it wasn't for the family I would've had no money at all, probably lost the house and everything else.
"There were stages where I did go to work, just to bring in a bit of money to put on electric or gas.
"[It was] tiring, hard, in fact it was exhausting, I was already exhausted from having all the chemo, and it was just a case of right we need to get some electric, gas, so I had to find a bit of work and just go and plod along and do it."
The inquiry has revealed that this balance between accessing treatment and making ends meet is a common challenge for cancer patients in deprived areas.
Cancer Research UK's senior external affairs manager in Wales, Andy Glyde, said: "There are a lot of barriers that are contributing to people finding it more difficult to access health services.
"They might be less aware of the signs and symptoms of cancer, they might find it more difficult to get to an appointment from the GP.
"When they get to cancer diagnosis and treatment, there are lots of appointments involved. If you rely on public transport, if you're unable to take time off work particularly easily, it can make it a really tough choice in terms of being able to get to those appointments which is going to affect your chances of beating cancer."
The charity is calling for urgent action from the Welsh Government.
"This situation is unacceptable, we need to tackle cancer inequalities, and we know what some of the solutions are," Mr Glyde said.
"If we can start tackling smoking rates, which is much more prevalent in areas of deprivation, if we can introduce lung screening in Wales at a much faster pace, these are things that will really help us tackle cancer inequalities here in Wales and make sure everyone has the same chance of beating cancer."
The Welsh Government has said it will consider the report's recommendations.
A spokesperson said: "We are committed to addressing health inequalities and improving cancer services and survival rates.
We fund a number of projects to improve public health, including our Health Weight Healthy Wales strategy and Tobacco Control strategy, as well as our broader work to address poverty and risk factors such as air pollution."